There are two different points of view with regard to chicken food.
The industrial keepers argue that the kind of food you use is very important because the hens probably lay some more eggs per year when given special food.
They have is a special program to determine what time you should feed which hen with which food.
Thats a way you can do it, but I think it is too much work, as long as you keep your chickens in a natural environment.

I for my part feed only grains, consisting of corn and add some food with a high protein content to improve the laying performance.
Besides, I feed kitchen scraps such as potatoes, bread, eggshells (for better development of the eggshell), noodles, and whatever humans eat. Especially rice and salad are favorite chickens meals.
The water should be daily fresh in a clean bowl. In the winter a hotplate to warm the water does a good job.